Not Applicable
Not Applicable
(1) Field of the Invention
The present invention relates to an improved counterbalance apparatus for use in moving a work surface. In particular, the present invention relates to an improved counterbalance apparatus for vertically moving the work surface of a work station where the counterbalance apparatus exerts a constant force on the moving work surface.
(2) Description of the Related Art
Applicant""s Pat. Nos. 5,718,406 and 6,026,755 describe counterbalance apparatuses which apply a constant force on the work surface while the work surface is moving. The apparatus includes inner and outer members having inner and outer cam grooves. The apparatuses also have a dampener around which is mounted a spring. A cam follower having inner and outer cam rollers is connected to one end of the dampener. As the apparatuses are extended and compressed to raise and lower the work surface, the inner member moves in and out of the outer member which expands and compresses the spring. In addition, the inner rollers of the cam follower move along the inner grooves of the inner member and the outer cam rollers move along the outer grooves of the outer member. The cam rollers of the cam follower move together as a single unit. The cam rollers remain in their respective positions on the cam follower as the cam follower moves along the grooves in the inner and outer members.
Other related art has shown various systems and mechanisms for vertically adjusting work surfaces or table tops. Illustrative are U.S. Pat. No. 484,707 to Garee; U.S. Pat. No. 2,649,345 to Hubbard; U.S. Pat. No. 4,130,069 to Evans et al; U.S. Pat. No. 4,183,689 to Wirges et al; U.S. Pat. No. 4,381,714 to Henneberg et al; U.S. Pat. No. 4,619,208 to Kurrasch; U.S. Pat. No. 4,651,652 to Wyckoff; U.S. Pat. No. 5,243,921 to Kruse et al; U.S. Pat. No. 5,322,025 to Sherman et al; U.S. Pat. No. 5,443,017 to Wacker et al and U.S. Pat. No. 5,456,191 to Hall.
In addition, U.S. Pat. Nos. 5,400,721 and 5,311,827 both to Greene show a load compensator for a spring counterweight mechanism which includes a snail cam.
U.S. Pat. No. 660,868 to Reid shows a counterbalance system for a table top which uses a chain and pulley with a weight. Similarly, U.S. Pat. No. 3,543,282 to Sautereau describes a drawing board having a counterbalance mechanism which includes pulleys and cables and which allows for easier vertical movement of the drawing board. U.S. Pat. No. 4,156,391 to Ubezio describes a counterbalance apparatus for table tops which uses a leaf spring as the means for providing the counterbalancing force. U.S. Pat. No. 4,351,245 to Laporte describes a counterweight system which uses cables and pulleys in combination with a cam mechanism.
Also, of some interest are U.S. Pat. No. 2,918,273 to Whisler et al and U.S. Pat. No. 3,582,059 to Van Ooy. Whisler et al shows a control device for a spring. Van Ooy describes a shock absorber where the wire of the compression spring is provided with one or more roller shaped guide members coaxial with the wire and rotatable about it. The guide members around the compression spring substantially eliminate wear and noise owing to sliding friction.
Only of minimal interest are U.S. Pat. No. 300,887 to Owen; U.S. Pat. No. 424,711 to Homan; U.S. Pat. No. 3,845,926 to Wahls; U.S. Pat. No. 3,885,764 to Pabreza; U.S. Pat. No. 4,415,135 to French; U.S. Pat. No. 4,625,657 to Little et al and U.S. Pat. No. 5,513,825 to Gutqsell. Owen shows an adjustable trestle for supporting scaffolding. Homan shows an extendable lamp standard. Wahls shows a seat pedestal which uses a vertically extending double telescoping tube to raise and lower the seat. The pedestal also includes a toggle linkage locking mechanism for locking the pedestal at a given height.
Pabreza describes a telescoping seat pedestal which uses an elastomer block as a locking means. French describes a device for supporting a chair seat which uses a hydraulic cylinder. The hydraulic cylinder uses the flow of fluid to control the raising and lowering of the seat and the lack of fluid flow to lock the seat in place. Little et al shows a retractable keyboard support. Gutqsell shows a telescopic adjustable height apparatus having a locking means.
Also of some interest is United Kingdom Patent No. 281,884 to Coppock which shows a folding table having an adjustable height.
There remains the need for a counterbalance mechanism which is easy and inexpensive to manufacture and which provides a constant output force throughout the entire range of load on the work surface throughout the total travel of the work surface.
The present invention is a counterbalance apparatus for use in raising and lowering work surfaces or table tops. The counterbalance apparatus includes an outer member and an inner member telescopingly mounted together such that the inner member slides in and out of the open top of the outer member. The inner surface of the outer member is provided with an insert having outer cam surfaces and guide surfaces. The inner surface of the inner member is provided with an insert having inner cam surfaces and secondary surfaces. An inner roller mechanism having a torque compensation roller and an anti-cantilever roller is mounted on the bottom end of the inner member. The torque compensation rollers move along the guide edges of the outer insert and prevent the inner member from rotating as it moves into and out of the outer member. The anti-cantilever roller contacts the sidewall of the outer member if the inner member tilts in the outer member usually due to a unequal placement of the load on the work surface. The apparatus also has a dampener with three (3) springs which mount around the dampener. A rotatable cam follower having cam rollers is mounted at the bottom end of the dampener. The springs extend between the cam follower and an adjustment nut at the top end of the dampener. The springs are preferably non-linear and compensate for the weight of the work surface and any load on the work surface. The adjustment nut allows for adjusting the compression of the springs and then the initial force exerted by the springs based on the weight of the work surface and load. As the inner member moves in and out of the outer member, the cam follower rotates such that the cam rollers follow along the cam surfaces of the inner and outer cam inserts. The apparatus also includes an anti-racking mechanism which uses two (2) spools of steel wrap to ensure that when two (2) counterbalance apparatus are used the apparatus raise and lower the work surface in unison. The counterbalance apparatus can be mounted in one or as many legs as necessary to adequately raise the work surface. If more than one counterbalance is used then the counterbalance apparatus are preferably connected together such that the apparatuses raise and lower the work surface in unison. The counterbalance apparatus allows for vertical movement of the work surface at a constant force through the entire range of movement even when there is a load on the table top. The counterbalance apparatus allows for adjustment of the initial preload force on the apparatus to compensate for the amount of load on the work surface without changing the amount of force needed to move the work surface. The counterbalance mechanism is inexpensive to manufacture and durable and easy to use.
The present invention relates to a counterbalance apparatus, the improvement which comprises: a first tubular member defining a longitudinal axis and having a first end and a second end with at least one wall between the ends which forms the tubular member having an inner cavity, wherein a first cam surface is provided on the wall in the inner cavity and is inclined with respect to the longitudinal axis of the first tubular member; a second tubular member slidably mounted in the first tubular member so as to be along the longitudinal axis and having a first end and a second end and at least one wall between the ends forming an inner cavity, wherein a second cam surface is provided on at least one wall in the inner cavity of the second tubular member along the axis and is inclined with respect to the longitudinal axis of the first tubular member, wherein the first and second cam surfaces are oppositely inclined with respect to the longitudinal axis and wherein at least one of the second or first tubular members is movable along the longitudinal axis relative to the other of the tubular members to move the tubular members together; cam follower means mounted on and between the first and second cam surfaces, wherein the cam follower means moves on both cam surfaces simultaneously as the tubular members are moved together; and resilient means having opposed ends and mounted along and around the longitudinal axis of the tubular members so as to bias the tubular members apart and wherein the resilient means is shortened in length between the ends when the tubular members are moved together.
Further, the present invention relates to a work station with a counterbalance movable work surface and a support means for the work surface with a counterbalance apparatus between the support means and the work surface for the movement which comprises: the counterbalance apparatus including a first tubular member defining a longitudinal axis and having a first end and a second end with at least one wall between the ends which forms the tubular member, wherein a first cam surface is provided on the wall and is inclined with respect to the longitudinal axis of the first tubular member; a second tubular member slidably mounted in the first tubular member so as to be along the axis and having a first end and a second end and at least one wall between the ends, wherein a second cam surface is provided on the wall along the axis and is inclined with respect to the longitudinal axis of the first tubular member, wherein the first and second cam surfaces are oppositely inclined with respect to the longitudinal axis and wherein at least one of the second or first tubular members is movable along the longitudinal axis relative to the other of the tubular members to move the tubular members together; cam follower means mounted on and between the first and second cam surfaces, wherein the cam follower means moves on both cam surfaces simultaneously as the tubular members are moved together; and resilient means with opposed ends which are mounted along and around the longitudinal axis of the first tubular member so as to bias the tubular members apart and which is shortened in length between the ends of the resilient means when the tubular members are moved together; and locking means for securing the work surface of the work station against movement.
Still further, the present invention relates to a counterbalance apparatus, the improvement which comprises: a first tubular member defining a longitudinal axis and having a first end and a second end with at least one wall between the ends which forms the tubular member having an inner cavity, wherein a first cam surface is provided on at least one wall in the inner cavity and is inclined with respect to the longitudinal axis of the first tubular member; a second tubular member slidably mounted in the first tubular member so as to be along the axis and having a first end and a second end and at least one wall between the ends forming an inner cavity, wherein a second cam surface is provided on at least one wall in the inner cavity of the second tubular member along the axis and is inclined with respect to the longitudinal axis of the first tubular member, wherein the first and second cam surfaces are oppositely inclined with respect to the longitudinal axis and wherein at least one of the second or first tubular members is movable along the longitudinal axis relative to the other of the tubular members to move the tubular members together; cam follower mounted on and between the first and second cam surfaces, wherein the cam follower moves on both cam surfaces simultaneously as the tubular members are moved together; and force storage mechanism with opposed ends which is mounted along and around the longitudinal axis of the tubular members so as to bias the tubular members apart.